So,Once they are lost in response to a toxic sound or to an antibiotic it cannot be regenerated by natural means.

一旦因噪音或抗生素遭受损失,就难以再生。

斯坦福公开课 - 7个颠覆你思想的演讲课程节选

Actually, the truth is I sort of almost felt that once you were there, it's kind of easy to get lost there, to forget about it.

实际情况是,我觉得一旦你生活在那里，似乎很容易忘记这种冲突。

普林斯顿公开课 - 人性课程节选